1 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 DOI /s JOURNAL OF NEUROENGINEERING JNERAND REHABILITATION RESEARCH Open Access Mechanisms to increase propulsive force for individuals poststroke HaoYuan Hsiao 1*, Brian A Knarr 2, Jill S Higginson 3 and Stuart A Binder-Macleod 4 Abstract Background: Propulsive force generation is critical to walking speed. Trialing limb angle and ankle moment are major contributors to increases in propulsive force during gait. For able-bodied individuals, trailing limb angle contributes twice as much as ankle moment to increases in propulsive force during speed modulation. The aim of this study was to quantify the relative contribution of ankle moment and trailing limb angle to increases in propulsive force for individuals poststroke. Methods: A biomechanical-based model previously developed for able-bodied individuals was evaluated and enhanced for individuals poststroke. Gait analysis was performed as subjects (N = 24) with chronic poststroke hemiparesis walked at their self-selected and fast walking speeds on a treadmill. Results: Both trailing limb angle and ankle moment increased during speed modulation. In the paretic limb, the contribution from trailing limb angle versus ankle moment to increases in propulsive force is 74% and 17%. In the non-paretic limb, the contribution from trailing limb angle versus ankle moment to increases in propulsive force is 67% and 22%. Conclusions: Individuals poststroke increase propulsive force mainly by changing trailing limb angle in both the paretic and non-paretic limbs. This strategy may contribute to the inefficiency in poststroke walking patterns. Future work is needed to examine whether these characteristics can be modified via intervention. Keywords: Stroke, Gait, Propulsion, Speed, Ankle moment, Trailing limb angle Background Current gait rehabilitation for individuals poststroke focuses on increasing gait velocity because it is a powerful indicator of function and prognosis after stroke . Walking speed has been shown to be associated with community walking ability, and an increase in gait velocity that produces a transition to a higher level of ambulation results in better community participation and quality of life . Because walking speed is also a reliable and responsive measurement, many recent clinical trials that target improved walking use walking speed as a primary outcome measure . Thus, aiming to maximize walking speed is commonly a therapeutic goal. Previous studies have shown that walking speed is related to propulsive force, defined as the anterior component of the ground reaction force (AGRF) during gait * Correspondence: 1 Biomechanics and Movement Science Program, University of Delaware, 540 S. College Avenue, Suite 201F, Newark, DE 19716, USA Full list of author information is available at the end of the article . More importantly, a recent study showed that improvements in paretic propulsive force are correlated to changes in self-selected walking speed and changes in fastest comfortable walking speed following a 12-week locomotor intervention . Thus, paretic propulsive force can be modified through intervention and is related to the improvement in walking speed. Understanding the mechanism to increase propulsive force would allow for the design of rehabilitation strategies for improving paretic propulsion and ultimately lead to increase walking speed. There are two critical factors for propulsive force generation: ankle moment and the position of the center of pressure (COP) relative to the body center of mass (COM) . Peterson et al. showed that ankle moment is correlated to propulsive force for able-bodied individuals and in the non-paretic leg for individuals poststroke . This finding is consistent with previous studies that showed ankle plantarflexor muscle activity is associated with the propulsive force in the paretic limb  and that ankle moment is 2015 Hsiao et al.; licensee BioMed Central. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
2 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 2 of 8 related to walking speed . Another critical predictor for propulsive force is the position of the COP relative to the body COM. This relative position affects the orientation of the ground reaction force (GRF) vector and, therefore, determines the proportion of the GRF being distributed anteriorly. Tyrell et al measured trailing limb angle (TLA), defined as the angle between the lab s vertical axis and the vector from the 5 th metatarsal joint to the great trochanter, and found that stroke survivors increased peak TLA and propulsion as walking speed progressively increased . Similarly, another study measured the angle between the vertical and the vector from the COM of the foot to the COM of the pelvis. They found that this angle is an important predictor and is positively related to propulsive force during able-bodied and hemiparetic walking . Using a simplistic quasi-static model, our lab has determined the relative contribution of ankle moment and TLA to propulsive force in able-bodied individuals . We showed that the TLA contributes almost twice as much as ankle moment to increases in propulsive force when able-bodied individuals increase their walking speeds . However, individuals poststroke may adopt different strategies to increase their propulsive force compared with able-bodied individuals. The purpose of this study was to test the accuracy of our previous model and to quantify the relative contribution of ankle moment and TLA to increases in propulsive force for individuals poststroke. Methods A total of 24 individuals poststroke participated in this study (10 female; 15 left hemiparetic; average age 60 years; body weight 89 kg; stroke onset 5 years). Exclusion criteria included congestive heart failure, peripheral artery disease with claudication, diabetes not under control via medication or diet, shortness of breath without exertion, unstable angina, resting heart rate outside the range of 40 to 100 beats per minute, resting blood pressure outside the range of 90/60 to 170/90 mm Hg, inability to communicate with the investigators, pain in lower limbs or spine, total knee replacement, cerebellar involvement, and neglect (star cancellation test). Subjects that walked with a negative TLA at the instant of peak AGRF were also excluded from this study. This study was approved by the Institutional Review Board of the University of Delaware and each subject provided written informed consent for participation in this study. Experimental procedure Each subject walked at their self-selected (SS) and fast (FS) walking speeds wearing a safety harness that provided no body weight support. For safety, subjects were allowed to use a handrail located at the side of the treadmill. Verbal instructions on using the handrail as minimal as possible were provided. SS walking speed was defined as the subject s comfortable walking speed and FS walking speed was the fastest speed that subjects could maintain for 4 minutes of continuous walking. Gait analysis was performed on an instrumented split-belt treadmill (Bertec Corp., Columbus, OH, USA) recording three dimensional forces with two embedded 6 degree-of-freedom force plates capturing at 1080 Hz. Kinematic data were recorded with a 62 marker set and eight camera passive motion capture system that detects motion of the reflective markers at 60 Hz (Motion Analysis Corp., Santa Rosa, CA, USA). Data processing was completed using Cortex and Visual 3D (C-Motion Inc., Bethesda, MD, USA). Kinematic data were filtered using a bi-directional Butterworth lowpass filter at 6 Hz. Peak AGRF (F a ) was defined as the maximum AGRF during stance between the onset of the propulsion (anterior) phase of anterior-posterior ground reaction forces and toe-off. Ankle moment (M a ) was defined as the ankle plantarflexion moment during stance. TLA was defined as the angle between the laboratory s vertical axis and the vector joining the greater trochanter with the fifth metatarsal head (see  for more detailed description). Handrail forces in the vertical and horizontal directions were analyzed at the instant of peak paretic AGRF during each subject s fast walking speeds. The AGRF, ankle moment, and TLA at the instant of peak AGRF were used in our model. All data were averaged across strides with 30 seconds trial duration for a given speed. Model development and validation A model previously developed for able-bodied individuals  (see Eq.1, wheref a is the AGRF, M a is the ankle moment, and TLA is the trailing limb angle) was first applied to the data obtained from individuals poststroke in this study. This model was evaluated using data from the paretic and non-paretic leg at SS and FS walking speeds. The model explained between 54-70% of the variance in propulsiveforce;however,thetrendlineslopesforthemeasured versus the predicted propulsive forces were approximately 0.77, indicating that the model over-estimated propulsive force for individuals poststroke. F a ¼ 7:013M a sinðtlaþ ð1þ Thus, an enhanced model was developed for better accuracy. For the enhanced model, rather than using the constant, 7.013, a variable, d, was included to account for the lever arm length of the ground reaction force (Figure 1). In addition, TLA was replaced by TLAcop, the angle between the laboratory s vertical axis and the vector joining the greater trochanter with the COP, to provide a better estimation of the ground reaction force angle (Eq.2).
3 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 3 of M a1 Δ sintla cop þ ΔM a sintla cop1 ΔF a ¼ 6 d 1 þ Δd þδm a Δ sintla cop Δd M a1 sintla cop1 d 1 ð5þ Figure 1 Diagram of variables of interest. F a was the anterior component of the ground reaction force. M a was the ankle plantarflexion moment. COP was the center of pressure. TLA cop was measured as the angle between the laboratory s vertical axis and the vector joining the greater trochanter with the COP. d was the perpendicular distance from the ankle joint to the vector joining the greater trochanter with the COP. F a ¼ 1 d M asin TLA cop Using Eq.2, the increase in propulsive force was calculated: ΔF a ¼ F a2 F a1 ¼ 1 d 2 M a2 sintla cop2 1 d 1 M a1 sintla cop1 ; ð2þ ð3þ where Δ denotes the change from the SS to the FS session, subscript 1 denotes the value at the SS session and subscript 2 denotes the value at the FS session. Letting, sin TLA 2 =sintla 1 + Δ sin TLA, M a2 = M a1 + ΔM a, and d 2 = d 1 + Δd, weget 1 ΔF a ¼ d 1 þ Δd M ð a1 þ ΔM a Þ sintla cop1 þ ΔsinTLA cop 1 d 1 M a1 sintla cop1 Rearranging Eq.4, we get ð4þ Based on Eq.5, four components contribute to the 1 change in propulsive force: d 1 þδd M a1δ sintla cop, 1 d 1 þδd ΔM 1 a1 sintla cop1, d 1 þδd ΔM aδ sintla cop, and 1 d 1 þδd Δd d 1 M a1 sintla cop1. The first component represents the contribution of the changes in TLA to propulsive force. The second component represents the contribution of the changes in ankle moment to propulsive force. The third component represents the contribution from the interaction between changes in TLA and ankle moment. The last component represents the relative contribution from changes in lever arm length to propulsive force. Each of the above terms was calculated and negative values were set to 0 (no contribution). The relative contributions were then calculated by dividing each term by the sum of all 1 terms. Note that d 1 þδd would have no impact on the relative contributions because it exists in all terms and would be cancelled out during the calculation. Model validation and statistical analysis Pearson s correlation coefficients (r) were calculated by comparing the predicted to the measured peak AGRF to evaluate the ability of the model to predict propulsive force for all subjects at two different speeds. The slopes of the trendlines were calculated by setting the intercepts to 0. In addition, a paired t-test was used to detect whether differences exist between the predicted and the experimental changes in peak AGRF. A 1-tailed paired t-test was used to detect increases in biomechanical measurements from SS to FS. The significance level was set at an alpha of Results The model predicted peak AGRF was the product of ankle moment and sin (TLA cop ) divided by the lever arm length (d) (Eq. 2). We validated the model in both the paretic and non-paretic leg at SS and FS walking speeds (Figure 2). The enhanced model explained more than 75% of the variance in propulsive force with the trendlines slopes close to 1. Model predicted changes in propulsive force were calculated from Eq.3. This model also explained more than 75% of the variance in changes in propulsive force with speed (Figure 3). No significant differences were found between the predicted (mean: paretic = N, non-paretic = N) versus the measured (mean: paretic = 20.1 N, non-paretic = N) changes in propulsive force (t = 1.34, p = 0.19 for the paretic and t = -0.53, p = 0.6 for the non-paretic).
4 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 4 of 8 The participants demonstrated a range of walking speeds (Table 1) and biomechanical measurements (Figure 4). Walking speed increased 26%. Significant increases were observed in all biomechanical variables (p < 0.01 for AGRF, TLA cop, d, and p < 0.05 for ankle moment) in both limbs. The relative contributions of the four components of Eq.5 to increases in propulsive force were quantified for each limb (Table 1). For the paretic limb propulsion, on average, the contributions of changes in TLA, ankle moment, lever arm length, and the interaction between TLA and ankle moment to increases in propulsive force were 74%, 17%, 2%, and 7%, respectively (Table 1). Thus, the ratio of the contribution of TLA versus ankle moment to increases in paretic propulsion was approximately 4:1. One subject (#24) did not increase paretic propulsive force during speed modulation. Eight subjects showed that the increases in TLA contributed more than 95% of increases in paretic propulsive forces and 11 subjects showed less than 2% contribution from the ankle moment to the increased propulsive force. Three subjects showed greater contribution from ankle moment (93%, 77%, and 66%) to propulsive force than from TLA. For the non-paretic limb, on average, the contribution of changes in TLA, ankle moment, lever arm length, and the interaction between TLA and ankle moment to increases in propulsive force were 67%, 22%, 6%, and 5%, respectively (Table 1). Thus, the ratio of the contribution of TLA versus ankle moment to increases in non-paretic propulsion was approximately 3:1. One subject (#13) did not increase non-paretic propulsive force during speed modulation. Five subjects showed that increases in TLA contributed more than 95% of increases in non-paretic propulsive forces and 7 subjects showed less than 2% contribution from the ankle moment to the increased propulsive force. One subject (#6) had a minor increase in propulsive force with decreased lever arm length and no increase in TLA or ankle moment. Three subjects showed greater contributions from increases in ankle moment (58%, 65%, and 63%) than from increases in TLA. Discussion In this study we found that the biomechanical-based model developed from able-bodied individuals (using ankle moment and TLA to predict propulsive force) over-estimated the propulsive force in stroke survivors. Thus, an enhanced model was developed and validated to describe the relationships between ankle moment, TLA (measured from the center of pressure), lever arm length between the GRF and the ankle joint, and propulsive force. The main finding was that individuals poststroke increase their propulsive force mostly by increasing TLA with relatively little contribution from ankle moment. In contrast to our previous model developed from able-bodied individuals, the lever arm length of the GRF was included as a variable in the present model. Because the lever arm length can vary with the position of the ankle joint, the position of the COP, and the angle of the GRF vector (Figure 1), this length is likely to be different Figure 2 Relationships between the measured and predicted peak anterior ground reaction force (AGRF). (A) Paretic propulsion during self-selected walking speed. (B) Non-paretic propulsion during self-selected walking speed. (C) Paretic propulsion during fast walking speed. (D) Non-paretic propulsion during fast walking speed.
5 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 5 of 8 Figure 3 Relationships between the measured and predicted changes in peak anterior ground reaction force (AGRF). (A) Changes in paretic propulsion. (B) Changes in non-paretic propulsion. across individuals and to change with walking speeds. The present study showed that this length increased during speed modulation (Figure 4). In addition, rather than measure TLA from the great trochanter to the 5 th metatarsal, the present study measured to the foot s COP. Measuring TLA to the COP allowed our model to capture the variance in COP position at late stance and therefore enhanced our model. For a population with a wide range in joint angles and COP positions, such as stroke survivors, variations across walking speeds and among individuals in these parameters can be large and, therefore, needed to be considered. Participants in this study showed a range of self-selected walking speeds from 0.27 to 1.51(m/s) and fast walking speeds from 0.4 to 1.68(m/s). Thus, the present model seemed to work for a wide range of walking speeds. In agreement with previous studies, the present results showed that individuals poststroke increased TLA and peak AGRF at their fast walking speeds. Tyrell and colleagues observed increases in peak hip extension angle and peak TLA in the paretic limb when individuals poststroke progressively increased their walking speeds . Similarly, increases in paretic peak TLA and AGRF during fast speed were also reported in a previous study of the effects of fast treadmill walking on poststroke gait . Changes in TLA observed in this study were greater than the within-session minimal detectable change (1 ) for this variable . Also consistent with previous studies, increases in ankle plantarflexion moment were observed at the fast speed in the present study. Nadeau and colleagues found an increase in muscle utilization ratio, the ratio of the ankle plantarflexion moment used during gait to the maximal moment estimated from dynamometric measurements , at the fast walking speed in chronic stroke survivors . However, in a study of the relationship between joint power and walking speeds in individuals poststroke, increases in paretic ankle plantarflexion power at fast walking speed were only significant for the higher functioning group . Interestingly, although our results showed an average increase in ankle moment, 10 of 24 subjects did not increase their paretic ankle moment and 7 subjects did not increase their non-paretic ankle moment at the fast speed compared with their self-selected speed. In the paretic limb, the majority of the change in propulsive force was contributed from the change in TLA (74%); relatively little contribution from ankle moment (17%) was observed in the paretic leg during speed modulation (Table 1). This finding is similar to our previously reported results in able-bodied individuals that showed that TLA was the major contributor (66%) to increases in propulsive force during speed modulation . One possible explanation of this greater contribution from TLA could be due to the weakness or inability to modulate the force in the paretic ankle plantarflexor muscles in stroke survivors. Jonkers and colleagues found that lower functioning hemiparetic subjects engaged excessive plantarflexor power generation at SS walking speeds and therefore no further increase was revealed during the fast walking speed condition . The inability to modulate ankle plantarflexor muscles in individuals poststroke may only allow them to modulate TLA to increase propulsive force. Our results showed a wide variation of contributions from the paretic ankle moment to increases in propulsive force across individuals. Interestingly, in contrast to what we had anticipated, the average walking speed for the 10 subjects who showed no contribution from ankle moment to the increase in propulsion was substantially higher than the average walking speed of the rest of 14 subjects (1.0 versus 0.66 m/s). In fact, subjects 18 and 22 increased both paretic and non-paretic propulsion without increasing ankle moment, yet both of these individuals were amongst the 5 th fastest walkers. Thus, individuals who adopted the TLA strategy to increase propulsive force were not only limited to slower ambulators. In the non-paretic limb, the contribution from TLA (67%) to the increase in propulsive force was also greater than the contribution from ankle moment (22%). Thus,
6 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 6 of 8 Table 1 Walking speeds and relative contributions to increases in propulsive force from changes in each variables Subject Age (yrs) SS (m/s) FS (m/s) Relative contribution to paretic propulsion Relative contribution to non-paretic propulsion Handrail forces/bw TLA M a mix d TLA M a mix d Vertical Horizontal N/A N/A N/A N/A N/A N/A N/A N/A * * Mean SD max min SS = self-selected walking speed, FS = fast walking speed, TLA = trailing limb angle, M a = ankle moment, mix = interaction term, d = lever arm length. N/A denotes that handrail forces data not available. Handrail forces were normalized by bodyweight. Positive values of handrail forces in the vertical and horizontal direction indicate forces pointing downwards and backwards, respectively. *Subject#24 did not increase paretic propulsive force and subject#13 did not increase non-paretic propulsion during speed modulation. Thus, the relative contributions of the variables for these two subjects were not included in the overall averages in Table 1. on average, the ratio of the contribution of TLA versus ankle moment to the increase in propulsive force was about 3:1 in the non-paretic limb and 4:1 in the paretic limb. This ratio in the non-paretic limb is closer to the ratio reported in able-bodied individuals (2:1). In addition, compared to the paretic limb, fewer subjects adopted the strategy that uses TLA alone to increase propulsive force on their non-paretic limbs. For individuals post-stroke, the rate of force development and voluntary activation of the plantarflexor muscle has been shown to be considerably reduced in the paretic limb compared to the nonparetic limb . Investigations on whether improving paretic ankle plantarflexor strength will modify the strategy adopted to increase propulsion would provide insight into the reason why individuals select particular strategies to increase propulsion. Although changing TLA alone may allow for increasing propulsive force without requiring additional force to be generated from the ankle plantarflexor muscles, the lack of push-off force may eventually lead to more mechanical work being needed to complete the redirection of the COM velocity during the step to step transition [16,17]. Using a simple walking model, Kuo studied the mechanical energy needed to overcome energetic losses incurred
7 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 7 of 8 Figure 4 Means and standard errors of the measured variables in both limbs at self-selected (SS) and fast (FS) walking speeds (N = 24). White bars represent data from SS and black bars represent data from FS. (A) AGRF normalized by body weight. (B) Trailing limb angle. (C) Ankle moment normalized by body weight. (D) Lever arm length for GRF. * p 0.05 and ** p at heel strike and found that an impulse applied to the stance foot immediately before heel strike is four times less costly than driving the stance leg via torque at the hip . Thus, the excessive reliance on increasing TLA and the concomitant increase in hip torque alone, rather than also increasing ankle moment to increase propulsive force, may demand more mechanical work for individuals poststroke. Future investigation to determine if greater mechanical work is actually observed for individuals who depend on TLA alone to increase propulsive force during gait is needed. It is worth noting that although the average increases in TLA reported from this study were comparable to the previously reported values in able-bodied individuals, the TLA at self-selected and fast walking speeds in this study were still relatively small compared with able-bodied individuals . That is, stroke survivors still need to improve TLA to restore normal walking pattern. However, for individuals who do not increase their ankle moment to increase propulsion, gait interventions targeting improving TLA may lead to a more energy inefficient gait. Thus, the capacity to increase ankle plantarflexion moments may be a criteria to evaluate individuals who will benefit most from interventions that increases walking speed or propulsion. One factor that the present study did not measure is risk of falling. Although physiological constraints such as muscle strength or energy cost are important factors in gait, preference of strategy may be influenced by fear of falling . For example, if increasing ankle moment to increase walking speed could lead to increase in risk of falling, individuals poststroke may avoid this strategy regardless of metabolic efficiency. Thus, future investigation measuring balance in conjunction with TLA and ankle moment is important for understanding the mechanism individual select to increase propulsion and for directing gait intervention. There were limitations in this study. First, our model was not applicable for individuals who did not position their feet posterior to their body at terminal stance. A foot position anterior to the COM would result in a negative TLA. Based on our model, a negative TLA would produce a posterior ground reaction force and therefore generate a braking force rather than a propulsive force. Thus, individuals with negative TLA were excluded from this study. Second, subjects participating in this study were allowed to hold onto the handrails. The use of handrails could influence gait patterns and force distribution. For example, subjects could use the handrail to support part of their
8 Hsiao et al. Journal of NeuroEngineering and Rehabilitation (2015) 12:40 Page 8 of 8 body weight and therefore decrease the force needed from their legs. In addition, the use of a handrail may cause individuals to lean their body toward the handrail rather than staying upright. This body leaning may affect the angle of the ground reaction force without being captured by our model as TLA and ankle moment did not account for upper body movements. Thus, the accuracy of our model could be affected by handrail use. However, verbal instructions on using the handrail as minimal as possible were provided during data collection. Our results showed that the handrail forces were subject-specific and were not correlated to mechanisms of increasing propulsion (see Table 1). For example, subjects#12, #18 and #21 used similar handrail forces but very different lower extremity strategies to increase propulsion. Another potential limitation in this study was the sensitivity of our model. Three participants had small increases in walking speed from selfselected to fast (subjects #1, #6, and #13). Each of these subjects showed large contributions from changes in the lever arm length. Thus, our model may not be suitable for analyzing very small increases in walking speeds. Finally, the present study did not have an age-matched control group and therefore could not exclude the effect of age on mechanisms to increase propulsion. Thus, future studies comparing individuals poststroke and age-matched ablebodied individuals are needed. However, based on the data presented in Table 1, there was no obvious relationship between subjects ages (range: years) and the mechanism for increasing propulsion. Conclusions This is the first study that quantified the relative contribution of ankle moment and TLA to the increase in propulsive force during poststroke gait. By enhancing a previously developed biomechanical-based model, the present results showed that individuals poststroke increase propulsive force mainly by changing TLA for both the paretic and non-paretic limbs. In addition, the present model has the potential application to determine the mechanism used to improve propulsive force pre and post intervention. Abbreviations AGRF: Anterior ground reaction force; COP: Center of pressure; COM: Center of mass; GRF: Ground reaction force; TLA: Trailing limb angle; SS: Self-selected; FS: Fast. Competing interests The authors declare that they have no competing interests. Authors contributions All authors have substantive intellectual contributions to model developing and manuscript drafting. All authors read and approved the final manuscript. Acknowledgement We thank Louis Awad, Christopher Cutsail, and Kevin Lenoir for data collection and processing. Source of funding NIH R44HD062065, NIH R01HD038582, and NIH RO1 NR Author details 1 Biomechanics and Movement Science Program, University of Delaware, 540 S. College Avenue, Suite 201F, Newark, DE 19716, USA. 2 Delaware Rehabilitation Institute, Newark, DE 19716, USA. 3 Department of Mechanical Engineering, University of Delaware, Newark, DE 19716, USA. 4 Department of Physical Therapy, University of Delaware, Newark, DE 19716, USA. Received: 13 January 2015 Accepted: 7 April 2015 References 1. Schmid A, Duncan PW, Studenski S, Lai SM, Richards L, Perera S, et al. Improvements in speed-based gait classifications are meaningful. Stroke. 2007;38: Dobkin BH, Plummer-D Amato P, Elashoff R, Lee J. International randomized clinical trial, stroke inpatient rehabilitation with reinforcement of walking speed (SIRROWS), improves outcomes. Neurorehabil Neural Repair. 2010;24: Bowden MG, Balasubramanian CK, Neptune RR, Kautz SA. Anterior-posterior ground reaction forces as a measure of paretic leg contribution in hemiparetic walking. Stroke. 2006;37: Bowden MG, Behrman AL, Neptune RR, Gregory CM, Kautz SA. Locomotor rehabilitation of individuals with chronic stroke: difference between responders and nonresponders. Arch Phys Med Rehabil. 2013;94: Peterson CL, Cheng J, Kautz SA, Neptune RR. Leg extension is an important predictor of paretic leg propulsion in hemiparetic walking. Gait Posture. 2010;32: Turns LJ, Neptune RR, Kautz SA. Relationships between muscle activity and anteroposterior ground reaction forces in hemiparetic walking. Arch Phys Med Rehabil. 2007;88: Olney SJ, Griffin MP, McBride ID. Temporal, kinematic, and kinetic variables related to gait speed in subjects with hemiplegia: a regression approach. Phys Ther. 1994;74: Tyrell CM, Roos MA, Rudolph KS, Reisman DS. Influence of systematic increases in treadmill walking speed on gait kinematics after stroke. Phys Ther. 2011;91: Hsiao H, Knarr BA, Higginson JS, Binder-Macleod SA. The relative contribution of ankle moment and trailing limb angle to propulsive force during gait. Hum Mov Sci. 2015;39: Kesar TM, Reisman DS, Perumal R, Jancosko AM, Higginson JS, Rudolph KS, et al. Combined effects of fast treadmill walking and functional electrical stimulation on post-stroke gait. Gait Posture. 2011;33: Kesar TM, Binder-Macleod SA, Hicks GE, Reisman DS. Minimal detectable change for gait variables collected during treadmill walking in individuals post-stroke. Gait Posture. 2011;33: Nadeau S, Gravel D, Arsenault AB, Bourbonnais D. A mechanical model to study the relationship between gait speed and muscular strength. IEEE Trans Rehabil Eng. 1996;4: Nadeau S, Gravel D, Arsenault AB, Bourbonnais D. Plantarflexor weakness as a limiting factor of gait speed in stroke subjects and the compensating role of hip flexors. Clin Biomech (Bristol, Avon). 1999;14(2): Jonkers I, Delp S, Patten C. Capacity to increase walking speed is limited by impaired hip and ankle power generation in lower functioning persons post-stroke. Gait Posture. 2009;29: Fimland MS, Moen PMR, Hill T, Gjellesvik TI, Tørhaug T, Helgerud J, et al. Neuromuscular performance of paretic versus non-paretic plantar flexors after stroke. Eur J Appl Physiol. 2011;111: Huang Y, Meijer OG, Lin J, Bruijn SM, Wu W, Lin X, et al. The effects of stride length and stride frequency on trunk coordination in human walking. Gait Posture. 2010;31: Soo CH, Donelan JM. Coordination of push-off and collision determine the mechanical work of step-to-step transitions when isolated from human walking. Gait Posture. 2012;35: Kuo AD. Energetics of actively powered locomotion using the simplest walking model. J Biomech Eng. 2001;124: Barak Y, Wagenaar RC, Holt KG. Gait characteristics of elderly people with a history of falls: a dynamic approach. Phys Ther. 2006;86:
Clinical biomechanics of gait Outline terminology related to the gait cycle determinants of gait muscle activity during gait joint rotations, joint torques, and joint power during gait KIN 201 2007-1 Stephen
Gait Cycle: The period of time from one event (usually initial contact) of one foot to the following occurrence of the same event with the same foot. Abbreviated GC. Gait Stride: The distance from initial
Biomechanics IPHY 4540 Problem Set #10 For all quantitative problems, please list all known variables, the variables that you need to find, and put a box around your final answers. Answers must include
Gait Review of Last Lecture - TE Interventions to increase flexibility Generating muscle force depends on Open chain vs. closed chain PNF Balance strategies Benefits of aerobic exercise Gait An individual
Link Segment Analysis Net Muscle Moments and Net Joint Forces Back Moments So far we have focused on back moments with simple models that assumed we knew the location of the upper body centre of gravity.
SUMMARY This PhD thesis addresses the long term recovery of hemiplegic gait in severely affected stroke patients. It first reviews current rehabilitation research developments in functional recovery after
CHAPTER 5 BALANCE SUPPORT AFTER STROKE The effect of balance support on the energy cost of walking after stroke IJmker T, Houdijk H, Lamoth CJ, Jarbandhan AV, Rijntjes D, Beek PJ, van der Woude LH. Archives
A Gender Comparison of Lower Extremity Landing Biomechanics Utilizing Different Tasks: Implications in ACL Injury Research Adam Hernandez Erik Swartz, PhD ATC Dain LaRoche, PhD Anterior Cruciate Ligament
International Neurorehabilitation Symposium February 12, 2009 The Use of the Lokomat System in Clinical Research Keith Tansey, MD, PhD Director, Spinal Cord Injury Research Crawford Research Institute,
GRF and Kinematics of Sprint Running 31 JOURNAL OF APPLIED BIOMECHANICS, 2005, 21, 31-43 2005 Human Kinetics Publishers, Inc. Relationships Between Ground Reaction Force Impulse and Kinematics of Sprint-Running
Hip Rehab: Things to Consider Sue Torrence, MS, PT, ATC Lead Physical Therapist Where to Start? Objectives: Discuss injuries related to hip dysfunction Review commonly used functional tests for posteriolateral
KIN 335 - Biomechanics LAB: Ground Reaction Forces - Linear Kinetics Reading Assignment: 1) Luhtanen, P. and Komi, P.V. (1978). Segmental contribution to forces in vertical jump. European Journal of Applied
Purpose: Lab #7 - Joint Kinetics and Internal Forces The objective of this lab is to understand how to calculate net joint forces (NJFs) and net joint moments (NJMs) from force data. Upon completion of
Biomechanical Principles in Sprint Running Basic Concepts Iain Fletcher Content Stride Length Stride Frequency Newton s Laws Running Mechanics How to Run Faster!! Asafa Powell 9.77s Running Speed Stride
Pathological Gait I: Musculoskeletal - 1 PATHOLOGIC GAIT -- MUSCULOSKELETAL Normal walking is the standard against which pathology is measured Efficiency is often reduced in pathology COMMON GAIT ABNORMALITIES
This article was downloaded by: [University of Nebraska at Omaha], [Nick Stergiou] On: 20 April 2012, At: 12:35 Publisher: Taylor & Francis Informa Ltd Registered in England and Wales Registered Number:
Biomechanics of Lifting and Outline Lower Back Pain: part 2 Spinal stability Shear forces S.N. Robinovitch Effect of abdominal pressure on lifting mechanics Cantilever model of lifting Forces on the lumbar
University of Salford: An Introduction to Clinical Gait Analysis 1.1 Temporal spatial data, the gait cycle and gait graphs Richard Baker Temporal spatial parameters Distance parameters Human walking is
BESTest Balance Evaluation Systems Test Fay Horak PhD Copyright 2008 TEST NUMBER/SUBJECT CODE DATE EXAMINER NAME EXAMINER Instructions for BESTest 1. Subjects should be tested with flat heeled shoes or
13 ORIGINAL ARTICLE Metabolic and Mechanical Energy Costs of Reducing Vertical Center of Mass Movement During Gait Keith E. Gordon, PhD, Daniel P. Ferris, PhD, Arthur D. Kuo, PhD ABSTRACT. Gordon KE, Ferris
Pol. J. Sport Tourism, 9, 8-7 DOI:.78/v97---z 8 Original research papers THE IMPACT OF ANKLE JOINT STIFFENING BY SKI EQUIPMENT ON MAINTENANCE OF BODY BALANCE The impact of ski equipment on body balance
Spine Care Centre (SCC) protocols for Multiple Sclerosis Update 1 August 2015 Introduction Multiple sclerosis (MS) affects nerves in the brain and spinal cord, causing a wide range of symptoms including
ARTICLE Energetic Consequences of Walking Like an Inverted Pendulum: Step-to-Step Transitions Arthur D. Kuo, 1 J. Maxwell Donelan, 2 and Andy Ruina 3 1 Departments of Mechanical Engineering & Biomedical
Adapted Therapeutic Balance Training for Fall Prevention in Older Adults: A Guide to Tai Ji Quan: Moving for Better Balance for Health Care Professionals Fuzhong Li, Ph.D. Program Creator Oregon Research
Treadmill walking with body weight support Odense 27.10.12 Mona K. Aaslund (PhD and specialist in Neurological Physiotherapy) Stroke rehabilitation Mobilisation should be repetitive, specific to everyday
Webinar title: What is the Vibe? Vibration Therapy as a Rehabilitation Tool Presenter/presenters: Kimberly Anderson-Erisman, PhD Director of Education University of Miami & Miami Project to Cure Paralysis
Journal of Rehabilitation Research and Development Vol. 30 No. 2 1993 Pages 210 223 'V"Ze Department of Veterans Affairs A Technical Note Basic gait parameters : Reference data for normal subjects, 10-79
CORE STRENGTH EXERCISES The main muscles involved with Core Strength include muscles of the abdomen, hip flexors and low back postural muscles. It is important to maintain proper strength of these muscles
APPLICATIONS, BASIS & COMMUNICATIONS 186 BIOMECHANICAL ANALYSIS OF THE STANDING LONG JUMP WEN-LAN WU 1, JIA-HROUNG WIT, HWAI-TING LIN\ GWO-JAW WANG 4 1 School of Sports Medicine, Kaohsiung Medical University,
Physics 160 Biomechanics Newton s Laws Questions to Think About Why does it take more force to cause an object to start sliding than it does to keep it sliding? Why is a ligament more likely to tear during
CHAPTER 3 Functional ability and muscle force in healthy children and ambulant Duchenne muscular dystrophy patients. Functional ability and muscle force in healthy children and ambulant Duchenne muscular
Basic Biomechanics Biomechanics is the study of the body in motion. Foot biomechanics studies the relationship of the foot to the lower leg. During walking and running the musculoskeletal system generates
Abnormal Gait Review Last Lecture Definition of Gait? What are the 2 phases of gait? 5 parts of stance phase? 3 parts of swing phase? Abnormal Gait An altered gait pattern reflecting any lower extremity
THE INFLUENCE OF WALL PAINTING ON SHOULDER MUSCLE ACTIVITY AND HORIZONTAL PUSH FORCE Background: Patricia M. Rosati and Clark R. Dickerson Department of Kinesiology, University of Waterloo, Waterloo, ON
STROKE CARE NOW NETWORK CONFERENCE MAY 22, 2014 Rehabilitation Innovations in Post- Stroke Recovery Madhav Bhat, MD Fort Wayne Neurological Center DISCLOSURE Paid speaker for TEVA Neuroscience Program.
Aquatic Therapy and the ACL Current Concepts on Prevention and Rehab Mary LaBarre, PT, DPT,ATRIC Anterior Cruciate Ligament (ACL) tears are a common knee injury in athletic rehab. Each year, approximately
Research Report Lower-Extremity Strength Differences Predict Activity Limitations in People With Chronic Stroke Patricia Kluding, Byron Gajewski Background. Body system impairments following stroke have
Early Gait Training of the Person with a Lower Extremity Amputation Lateral weight transfer 1. Stand between the parallel bars with feet 2-4 inches apart (A). 2. Shift weight laterally from the sound leg
A New Outcome Measure for Spinal Cord Injury Based on Pre-injury Function, Not Compensation: Neuromuscular Recovery Scale Combined Sections Meeting 2013 San Diego, CA January 21-24, 2013 D. Michele Basso
Pattern Characterization of Running and Cutting Maneuvers in Relation to Noncontact ACL Injury Brenna Hearn During running and cutting maneuvers, the anterior cruciate ligament (ACL) is commonly injured
USING A WALKING TEST 12/25/05 PAGE 1 Predicting Aerobic Power (VO 2max ) Using The 1-Mile Walk Test KEYWORDS 1. Predict VO 2max 2. Rockport 1-mile walk test 3. Self-paced test 4. L min -1 5. ml kg -1 1min
Locomotion Skills Walking Running Horizontal Jump Hopping Skipping Walking Progressive alternation of leading legs and continuous contact with the supporting surface. Walking cycle or Gait cycle involves
User Guide MTD-3 Motion Lab Systems, Inc. This manual was written by Motion Lab Systems using ComponentOne Doc-To-Help. Updated Tuesday, June 07, 2016 Intended Audience This manual is written to provide
Mechanics of the Human Spine Lifting and Spinal Compression Hamill and Knutzen: Chapter 7 Nordin and Frankel: Ch. 10 by Margareta Lindh Hall: Ch. 9 (more muscle anatomy detail than required) Low Back Pain
Psoas Syndrome The iliopsoas muscle is a major body mover but seldom considered as a source of pain. Chronic lower back pain involving the hips, legs, or thoracic regions can often be traced to an iliopsoas
Chapman University Chapman University Digital Commons Physical Therapy Faculty Articles and Research Physical Therapy 2007 Influence of a Functional Knee Brace and Exercise on Lower Extremity Kinematics
Why Eccentrics? What is it? Eccentric adj., departing from the norm, not concentric, utilizing negative resistance for better client outcomes Eccentrics is a type of muscle contraction that occurs as the
GAIT PARAMETERS YOU CAN MEASURE IN THE CLINIC CADENCE: steps/minute Have patient walk 30 seconds and count each step, then multiply times 2. You can also just do this for 60 seconds. (Average speed for
Proportional EMG Control of Ankle Plantar Flexion in a Powered Transtibial Prosthesis Jing Wang, Oliver A Kannape, Hugh M Herr MIT Media Lab Massachusetts Institute of Technology Cambridge, MA 02139, USA
Basic Biomechanics the body as a living machine for locomotion What is Kinesiology? Kinesis: To move -ology: to study: The study of movement What the heck does that mean? Why do we need Kinesiology? As
ACTA PHYSICA DEBRECINA XLVI, 143 (2012) DINAMIC AND STATIC CENTRE OF PRESSURE MEASUREMENT ON THE FORCEPLATE F. R. Soha, I. A. Szabó, M. Budai University of Debrecen, Department of Solid State Physics Abstract
International Neurorehabilitation Symposium February 12, 2009 Neural Plasticity and Locomotor Recovery: Robotics in Research Keith Tansey, MD, PhD Director, Spinal Cord Injury Research Crawford Research
International Journal of Applied Science and Technology Vol. 2 No. 7; August 2012 Role of Upper Limbs: Slip-induced Falls Sukwon Kim, Ph.D Department of Physical Education Chonbuk National University Jeon-ju
John F. Schulte CPO FAAOP Has no financial interest or relationships to disclose CME Staff Disclosures Professional Education Services Group staff have no financial interest or relationships to disclose.
How to read Dashboard Reports The premise behind RPM 2 is to assess bilateral equivalence of the lower limbs. It has long been understood that bi-lateral equivalence is the key to improved athletic performance.
Read a chapter on Angular Kinematics Angular Kinematics Hamill & Knutzen (Ch 9) Hay (Ch. 4), Hay & Ried (Ch. 10), Kreighbaum & Barthels (Module Ι) or Hall (Ch. 11) Reporting Angles Measurement of Angles
Dr Stelios G. Psycharakis Dynamics of Vertical Jumps School of Life, Sport & Social Sciences, Edinburgh Napier University, Edinburgh, UK Introduction A vertical jump is a movement that is used in a plethora
RESEARCH ARTICLES Short-term Maximal-Intensity Resistance Training Increases Volitional Function and Strength in Chronic Incomplete Spinal Cord Injury: A Pilot Study Arun Jayaraman, PT, PhD, Christopher
International Neurorehabilitation Symposium, University Irchel, Zuerich, Switzerland, 12.2.-13.02.2009 Physiological mobilization of very acute SCI patients effects on the cardiovascular system R. Rupp,
1 2. P H Y S I C A L T H E R A P Y ( P T ) 12. Physical Therapy (PT) Clinical presentation Interventions Precautions Activity guidelines Swimming Generally, physical therapy (PT) promotes health with a
Indian Journal of Biomechanics: Special Issue (NCBM 7-8 March 2009) Prosthetic Foot Design for Transtibial Prosthesis Ranjan Das, M.D Burman, Sagar Mohapatra, Department of prosthetics & Orthotics, S.V.Nirtar,
Force and Motion Sections Covered in the Text: Chapters 4 and 8 Thus far we have studied some attributes of motion. But the cause of the motion, namely force, we have essentially ignored. It is true that
The Effects of Simulated Muscle Weakness on Lower Extremity Muscle Function during Gait in Healthy, Older Subjects Thesis Presented in Partial Fulfillment of the Requirements for the Degree Master of Science
Total Knee Arthroplasty Unicompartmental Knee Arthroplasty Monica Clarke P.T., FCAMPT Stittsville Sport Physiotherapy Centre Purpose of this presentation A version of this presentation was presented at
Metabolic cost of generating horizontal forces during human running YOUNG-HUI CHANG AND RODGER KRAM Locomotion Laboratory, Department of Integrative Biology, University of California, Berkeley, California
INFORMATION SOCIETIES TECHNOLOGY (IST) PROGRAMME Project Number IST-1999-10954 Project Title: Virtual Animation of the Kinematics of the Human for Industrial, Educational and Research Purposes Title of
Table of Contents Tab Principles of Body Mechanics and Movement... 1 Techniques of Proper Movement Positioning Techniques Bed Mobility Techniques Upright Mobility Techniques Wheelchair Considerations...
Proper Transfer Techniques For Healthcare Professionals PROGRAM GUIDE FOR HEALTH CARE ASSISTANTS 1 OPTIMIZING MOBILITY IN OLDER ADULTS PROGRAM DESCRIPTION This program focuses on the safe transfer techniques.
Authors: Simone V. Gill, OTR/L, PhD Ya-Ching Hung, PT, EdD Affiliations: From the Department of Occupational Therapy, Boston University College of Health and Rehabilitation Sciences: Sargent College, Boston,
by Argyrios Stampas, MD, Carolin Dohle, MD, and Elizabeth Dominick, PT, DPT, NCS Therapist Jennifer Metz (right) helps a patient use a body-weight support treadmill system. Up and Moving Blending dedication
DIVISION OF AGRICULTURE RESEARCH & EXTENSION University of Arkansas System Family and Consumer Sciences Increasing Physical Activity as We Age Exercises for Low Back Injury Prevention FSFCS38 Lisa Washburn,
Effect Of Running Shoes On Foot Impact During Running arxiv:1609.01813v1 [physics.med-ph] 7 Sep 2016 Henry Nassif Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge, MA
Sit stand desks and musculo skeletal health Katharine Metters Topics Sitting Standing Movement and activity Work and human change Sitting uses less energy Sitting provides support for the body to reduce
The Royal Military College - Duntroon Army Officer Selection Board Bridging Period Conditioning Program CONTENTS Page Contents i INTRODUCTION 1 FAQS 2 CYCLE 1: NEUROMUSCULAR CONDITIONING FOCUS (WEEKS 1
PC1221 Fundamentals of Physics I Lectures 9 and 10 he Laws of Motion Dr ay Seng Chuan 1 Ground Rules Switch off your handphone and pager Switch off your laptop computer and keep it No talking while lecture
Research Report Dynamic Resources Used in Ambulation by Children With Spastic Hemiplegic Cerebral Palsy: Relationship to Kinematics, Energetics, and Asymmetries Background and Purpose. The atypical walking
Objec:ves Movement Pa+ern Analysis and Training in Athletes Department of Physical Therapy and Human Movement Sciences Appreciate the importance of movement pa+ern analysis and training in treahng athletes
Biomechanical Analysis of the Deadlift (aka Spinal Mechanics for Lifters) Tony Leyland Mechanical terminology The three directions in which forces are applied to human tissues are compression, tension,
Flat foot and lower back pain Dr James Tang, MBA, BDS, LDS RCS General Dental Practitioner, NASM Corrective Exercise Specialist with special interest in postural dysfunction & lower back problems, Level
Performance Enhancement Training for the Post Rehabilitated Knee NSCA National Conference July 11, 2013 Robert A. Panariello MS, PT, ATC, CSCS Professional Orthopedic and Sports Physical Therapy Professional
Your consent to our cookies if you continue to use this website.